The inspector leading the hunt for weapons of mass destruction in Iraq received a round of applause from the House Intelligence Committee (search) Thursday morning even though he told lawmakers that no smoking gun has yet been found in the search, a Capitol Hill source told Fox News.

Speaking to reporters after a companion hearing on the Senate side late Thursday afternoon, CIA adviser and head of the Iraq Survey Group David Kay (search) said he is convinced that there will be more surprises to come.

"Don't be surprised by surprises in Iraq," Kay said, adding that a mission that size will always uncover startling information.

Kay did not reveal any bombshells but said that he had enough evidence to show that former Iraqi leader Saddam Hussein (search) had been violating U.N. disarmament resolutions up until as recently as this year, including by having very substantial chemical and biological weapons plans.

"At this point we have found substantial evidence of an intent of senior-level Iraqi officials, including Saddam, to continue production at some future point in time of weapons of mass destruction. We have not found at this point actual weapons," he said.

Kay said Iraq's nuclear weapons program appears to have been the least developed program uncovered so far, but the country did have bombs that could fly as far as 1,000 kilometers, much further than the 93-kilometer limit the U.N. had imposed on the country.

Kay said his team is still trying to determine the foreign influences that could have provided the liquid and solid fuels that would have flown medium-range missiles.

Earlier in the day Prime Minister Tony Blair (search) of the United Kingdom, one of the coalition partners in Iraq, said weapons inspectors, who have only been on the ground for three months, have only one threshold to consider.

"The crucial question Kay's report poses is whether it will disclose evidence that is a breach of the United Nations resolutions that would have triggered a war with U.N. support if that information had been before the U.N. last March," Blair said.

The Kay appearance came after Bush administration officials revealed last month that Kay was returning to Washington to spend time barreling through thousands of documents from Saddam's deposed regime.

According to a source with knowledge of the closed-door House meeting, when Kay was asked point-blank by one House member whether he had found any weapons of mass destruction, Kay said no. Asked if he is going to find any, Kay replied, "I don't know."

According to the source, Kay described having found a lot of documents, a lot of computer files and quantities of materials — like chemical agents — needed to make weapons of mass destruction.

Kay briefed House committee members for approximately two and a half hours, spending the first hour delivering written testimony and the remaining 90 minutes answering lawmakers' questions. The source said he did a "very thorough job."

He cautioned that he still has much ground to cover and suffers from obstacles such as an inadequate supply of Arab linguists.

"It's not going to be obvious. Just walking in the country is not going to reveal the truth, you have to work at it and work at it hard," Kay told reporters after his testimony.

The source said Kay told lawmakers he expects to submit a final report to CIA Director George Tenet (search) in September 2004, right in the middle of next fall's presidential campaign.

White House officials Thursday downplayed the importance of the session, saying Kay's mission remains very much a work in progress.

"This is a progress report, keep it in perspective. They continue to do their work. There's some 1,900 members of the Iraq Survey Group (search) who are going through a massive amount of documents, interviewing a number of people in Iraq, Iraqis and scientists, who have knowledge of Saddam Hussein's history of weapons of mass destruction. And so they continue to pull together a complete picture," White House Press Secretary Scott McClellan said.

Asked whether the intelligence relied on to justify the war had been off base, Defense Secretary Donald Rumsfeld said he had not seen anything that would lead him to think collectively the intelligence was inaccurate.

"I expect there to be considerable variations between what the intelligence suggested and what is eventually found on the ground. That's been true with intelligence since man began trying to gather intelligence. But I believed it then. I believe it now. We'll all know in good time," Rumsfeld said in a briefing with reporters.

One Republican senator suggested that whatever Kay reports, it will not diminish the strength of President Bush and Congress' decision to authorize war in Iraq.

"I think that we all made that decision in good faith. So I hope we do find remnants that show that there was an ongoing effort to make those weapons of mass destruction, but I also think events have overtaken that issue right now," said Sen. Kay Bailey Hutchison (search), R-Texas.

Some experts have suggested that Kay's group will find no evidence of actual weapons, and perhaps only documentation. For Sen. Jay Rockefeller, D-W.Va., ranking member of the Senate Intelligence Committee (search), that's not good enough.

"If he's talking about programs or ready-to-reconstitute weapons of mass destruction, that's a very different thing than what it was that the president said to us in the State of the Union when he implied in a sense that the situation in Iraq was of immediate threat to the United States and therefore we had to take pre-emptive action," Rockefeller said.

He added, however, that he is not prepared to make any final judgments until the report is wrapped up next year.

Lawmakers are continuing to investigate the quality of prewar intelligence. In a letter last week to Tenet, the two top members of the House intelligence panel said there were "significant deficiencies" in the collection of intelligence on Iraq's weapons programs and any ties Iraq may have had to Al Qaeda terrorists.

"There was a disconnect between public statements by administration officials and the underlying intelligence," read the letter sent by Chairman Porter Goss, R-Fla., and Rep. Jane Harman, D-Calif.

Kay's visit corresponds with Senate debate of President Bush's request for $87 billion for Iraq and Afghanistan. Democrats say the failure to find weapons calls into question whether the war, and its human and financial costs, were necessary.

Among the classified section of the request is a $600 million request to pay for the continued hunt for conclusive evidence of WMD, according to a New York Times report Thursday.

Fox News' James Rosen and The Associated Press contributed to this report.